Serum concentrations of oestradiol and progesterone and frequency of sexual behaviour during the normal oestrous cycle in the snow leopard (Panthera uncia) A. M. Schmidt, D. L. Hess, M. J. Schmidt and C. R. Lewis lMelro Washington Park Zoo, 4001 SW Canyon Rd, Portland, OR 97221, USA; and 2Division of Reproductive Science, Oregon Regional Primate Research Center, 505 NW 185th St, Beaverton, OR 97006, USA Serum oestradiol and progesterone concentrations were measured at weekly intervals for six months, and correlated with daily behavioural observations in two adult female snow leopards (Panthera uncia). Three oestradiol peaks (>21 pg ml\m=-\1; interval 3.6 weeks) were identified in a snow leopardess housed alone (two more were probably missed because of the weekly sampling schedule), and three oestradiol peaks were identified in a snow leopardess housed with a male as a breeding pair (interval 6 weeks). Daily frequencies of feline repro- ductive behaviour averaged 1.77 observations per observation period during weeks of high oestradiol and 0.62 during weeks of low oestradiol. Progesterone concentrations did not rise above baseline values ( < 2 ng ml\m=-\1) in the isolated animal, but 6 weeks of high progesterone concentrations 4.9\p=n-\38.8ng ml\m=-\1) was recorded in the paired snow leopardess following mating. No offspring were produced. Snow leopards were observed daily for an additional 4.5 years. Sexual behaviour peaks could be clearly identified from December through April, and average daily sexual behaviour scores were higher during these months than during the rest of the year. Intervals between sexual behaviour peaks for the isolated snow leopardess averaged 3.03 weeks. The sexual behaviour of the paired snow leopards decreased for 8\p=n-\9 weeks following mating when no offspring were produced, and decreased for 13 weeks in one year when a single cub was born. Introduction lions in captivity cycled throughout the year (Schmidt et al, 1979; Schmidt et al, 1988). female cats have not been studied in social situations. Analyses of serum hormone concentrations from members of Other data have been collected from a et the Felidae have demonstrated a spectrum of patterns associ¬ Hormonal jaguar (Wildt al, ated with their reproductive cycles. In domestic cats, seasonal, 1979), isolated pumas (Bonney et al, 1980) and isolated Siberian all these multiple oestrogen peaks occur which induce reproductive tigers (Seal et al, 1985). In felids, oestrogen surges behaviour (Michael, 1961; Michael and Scott, 1964; Leyhausen, were accompanied by reproductive behaviour and none of the was concentrations 1979) but these are not followed by ovulation or pro¬ oestrogen surges followed by progesterone peaks of ovulation. gesterone secretion unless mating or direct multiple cervical suggestive Information about the of snow is stimulation occurs (Longley, 1910; Greulich, 1934; Concannon reproductive cycle leopards et al, 1980; Wildt et al, 1980). In lions, in contrast, progesterone limited to observation of external events. Birth records and that secretion suggestive of ovulation was recorded after 6 of 8 observed behavioural oestrous cycles strongly suggest they are 1968; Marma and 1968; oestrogen surges in females isolated from males, but housed seasonal breeders (Freuh, Yunchis, 1971, 1977, 1983; Kitchener et al, 1975; Koivisto et together, and ovulation was recorded later in one isolated Freeman, lioness (Schmidt et al, 1979). Hormonal data collected from al, 1977; Rieger, 1982), which is logical considering their severe natural habitat. To our serial oestradiol and leopards in our laboratory suggest that female leopards will knowledge, pro¬ ovulate without cervical stimulation if housed together, but gesterone concentrations have not been measured during of the normal this there was no evidence of ovulation in isolated females (Schmidt phases reproductive cycle in species. This was undertaken to information on serum et al, 1988). These data suggest that although some impulse study provide oestradiol and concentrations in snow may trigger ovulation, not all Felidae require cervical stimu¬ progesterone leopards lation to induce ovulation. Reproductive behaviour in the housed as a breeding pair and in an isolated female during the normal We also to correlate in absence of a male suggested that female leopards and female cycle. attempted changes repro¬ ductive behaviour with changes in hormone concentrations, and Received 11 May 1992. to monitor those reproductive behaviour patterns throughout Downloaded from Bioscientifica.com at 10/01/2021 10:11:13AM via free access the year. We hoped to add information on the reproductive of examination of the total data set and apparent grouping physiology and behaviour of this endangered species, and of values above and below this point. Blood samples were to use this information to manage our snow leopards more collected once per week for six months, and the serum was effectively for breeding. frozen at 20°C for later analyses. The animals were — immobilized with ketamine HC1 (12-14 mg kg-1) and xylaxine (0.5—1 mg kg-1) by darting. Materials and Methods Hormone assays Animals Oestradiol and progesterone concentrations were measured Four adult snow leopards were observed over five years from as described previously (Schmidt et al, 1979) using antisera 1985 to 1989. The three snow leopardesses were: Natasha, who purchased from Holly Hills Biologicals (Hillsboro, Oregon). The was 8 years old at the start of the study and was nulliparous; oestradiol antiserum as raised against 6-keto-oestradiol-17-6- Chuma, who was 8 years old and had had one litter of cubs; and oxime—BSA in rabbits and crossreacted 28% with oestrone, 3% Omaha 6 who was included in the final two years of the behav¬ with oestriol and < 1% with common androgens, progestagens ioural phase of this study. Omaha 6 was 7 years old and had and corticoids. The progesterone antiserum was similarly raised previously had one litter of cubs. Piotr, the male snow leopard, against lla-hydroxyprogesterone-lla-hemisuccinate-BSAand was 11 years old at the start of the study, and had never sired crossreacted 2% with 17a- and 20a-hydroxyprogesterone, cubs prior to the study, although he had been housed with three desoxy-corticosterone and < 1% with other common andro¬ different females for breeding since 1978 and had been gens, oestrogens and corticoids. Chromatography (Resko et al, observed copulating with each of them. The intervals between 1975) on 1.0 g Sephadex LH-20 columns separated oestrone, breeding episodes were consistently 2 months, very similar oestradiol and progesterone from each other as well as from to pseudopregnancy in the domestic cat (Paape et al, 1975; common androgens and corticoids before assay. Various aliquots Verhage et al, 1976). All snow leopards were housed in the of pooled snow leopard serum were assayed after chromato¬ feline building of the Metro Washington Park Zoo in Portland, graphy and provided parallel displacement curves to the Oregon. standards in both assays. Addition of 25 pg oestradiol ml-1 and The breeding pair of snow leopards was housed together at 12.5 ng progesterone ml-1 to pools of snow leopard serum all times, and was exhibited daily in an outdoor area measuring yielded recoveries of 23.6 pg ml-1 and 12.2 ng ml-1 after 12 m x 12 m. Natasha was exhibited daily in an outdoor area subtraction of pre-existing steroid concentration. Serum measuring 14 m x 7 m as an isolated female. The animals were (100-500 µ ) was extracted with freshly distilled diethyl ether fed in adjacent indoor areas measuring 3 m x 2 m. Commercial and analysed for steroid content by radioimmunoassay after carnivore diet (Nebraska Brand Feline Diet, Animal Spectrum, Chromatographie purification. The values derived from the Inc., Lincoln, Nebraska) was fed six times per week, bones were standard curve were corrected for reagent blanks and extrac¬ offered once per week. Water was available ad libitum. tion/purification losses during chromatography. Average blank and recovery factors were determined in independent samples and were found to be 2.1 + 0.09 pg and 72.3 + 1.4% for the Behaviour oestradiol assay and 26.5 + 4.2 pg and 83 + 0.8% for the pro¬ gesterone assay, respectively. The limits of sample detection Snow leopards were observed for 45 min in the outdoor after correction were 2 pg per tube for oestradiol and 10—15 pg the the area every day for 5-year study except for days on per tube for progesterone. The intra- and interassay coefficients which serum samples were collected. Behaviour patterns were of variation for either assay did not exceed 12% as determined recorded in 1 min block periods. Each behaviour was scored by repeated analysis of our standard quality control pools of by the number of blocks in which it occurred. These daily rhesus monkey serum. behavioural data were averaged for each week by summing the daily frequency of each behaviour for the 3 days before and after the day of serum collection, then dividing by the number Results of observation days for the week. Daily frequencies of those behaviours generally agreed upon Weekly oestradiol concentrations as characteristic feline reproductive behaviours (Cooper, 1942; Michael, 1961; Ulmer, 1966; Kleiman, 1974; Wildt et al, 1978; During the 6 month study three oestradiol peaks > 21 pg ml~: Leyhausen, 1979; Schmidt et al, 1979, 1988; Schule et al, 1979; suggestive of oestrus were recorded in the isolated snow Seal et al, 1985) were examined to determine which, if any, leopard, Natasha (Fig. la) (range 33-60 pg ml-1). Two more were consistently associated with hormonal oestrus in the snow peaks (27 March 1985, 15 May 1985 Fig. la) were probably leopards. These behaviours included: rolling, rubbing head, missed (note behavioural peaks) due to the weekly blood sam¬ lordosis, being mounted, low growl, marking, urinating and pling schedule.